Hydraulic control apparatus for an automatic transmission

ABSTRACT

A hydraulic control apparatus, provided with a manual shift valve that outputs a forward range pressure and a reverse range pressure, and a linear solenoid valve that outputs an engagement pressure to the hydraulic servo that engages during reverse travel when energized, includes a fourth clutch relay valve that is interposed between the linear solenoid valve and the hydraulic servo. The fourth clutch relay valve communicates an engagement pressure of the linear solenoid valve to the hydraulic servo by locking in the normal position when a signal pressure of the solenoid valve is input, and communicates a reverse range pressure to the hydraulic servo by being switched to a fail position by the reverse range pressure during a failure in which the fourth clutch relay valve is de-energized. Thereby, it is possible to establish a reverse speed during a failure in which the solenoid valve is de-energized.

INCORPORATION BY REFERENCE

This application claims priority from Japanese Patent Application Nos.2005-378391, 2005-378389, and 2005-378390, all filed on Dec. 28, 2005,the disclosures of which, including the specifications, drawings andabstracts, are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hydraulic control apparatus for anautomatic transmission that is mounted, for example, in a vehicle, andin particular, relates to a hydraulic control apparatus for an automatictransmission that establishes a reverse speed by outputting anengagement pressure to the hydraulic servo of a friction engagementelement by a solenoid valve that is energized when traveling in reverseduring normal operation.

2. Description of the Related Art

Conventionally, a staged automatic transmission that is mounted, forexample, in a vehicle, enables establishing each shift speed duringforward travel and a reverse speed by controlling the engagement stateof a plurality of friction engagement elements (clutches and brakes) byusing a hydraulic control apparatus and establishing a transmission pathin the speed change mechanism for each shift speed. In such a hydrauliccontrol apparatus, a plurality of solenoid valves are provided thatregulate and output engagement pressures to respective hydraulic servosthat releasably engage the plurality of friction engagement elements,and the control of the multi-stage shifting described above is carriedout by engaging the friction engagement elements necessary to establishthe shift speeds by using the electronic control of these solenoidvalves (refer, for example, to Japanese Patent Application PublicationNo. JP-A-8-42681).

However, in the hydraulic control apparatus described above, in order toprevent the friction engagement elements from unintentionally engagingwhen, for example, a failure (damage) occurs, or in order to suppresselectrical consumption during travel, preferably a normally closed typevalve, which does not output oil pressure when not energized, is usedfor the solenoid valves described above. Thus, during normal operationin such a hydraulic control apparatus, when the shift range is changedto the forward range or the reverse range based on the operation of theshift lever, the necessary solenoid valves are energized and engagementpressures are supplied to the hydraulic servos of the frictionengagement elements that engage in the forward shift speeds or thereverse shift speed, respectively.

However, in the hydraulic control apparatus described above, when thesolenoid valves that are necessary for establishing the reverse speedremain de-energized due to, for example, some sort of failure, there isa problem in that the reverse speed is not established, that is, thereverse travel of the vehicle becomes impossible.

In such fail states in which the solenoid valves that are necessary forreverse speed are not energized, the following cases can be considered:the case in which a sensor that detects, for example, the shift range,fails, the shift range cannot be detected, and whether any of thesolenoid valves should be energized cannot be determined, and the casein which, for example, a severed wire or short occurs and anall-solenoids-off failure mode is set. In this all-solenoids-off failuremode, all of the solenoid valves are de-energized in order to preventthe friction engagement elements from engaging unintentionally when anysort of failure has been detected.

SUMMARY OF THE INVENTION

Thus, one object of the present invention to provide a hydraulic controlapparatus for an automatic transmission that enables establishing areverse speed by switching a range switching valve to a reverse rangeposition even when the solenoid valves that should be energized duringreverse travel are de-energized.

According to a first aspect of the present invention, the firstswitching valve communicates a first engagement pressure to the firsthydraulic servo by being locked in the normal position when the signalpressure of the signal pressure output solenoid valve is output, andeven during a failure in which the first engagement pressure controlsolenoid valve and the signal pressure output solenoid valve arede-energized, when the range switching valve is switched to the reverserange position, the reverse range pressure is communicated to the firsthydraulic servo by switching to the fail position due to the reverserange pressure. Thus, during normal operation, it is possible toestablish smoothly the reverse speed by supplying the first engagementpressure, which is output from the first engagement pressure controlsolenoid valve, to the first hydraulic servo, and even during a failure,it is possible to establish the reverse speed by supplying the reverserange pressure to the first hydraulic servo, and thus the vehicle cantravel in reverse even during a failure.

According to a second aspect of the present invention, the firstswitching valve includes a spool that is switched between a normalposition and a fail position, an urging device that urges the spooltoward the normal position, a first oil chamber in which the signalpressure of the signal pressure output solenoid valve acts on the spoolin the direction of the normal position, and a second oil chamber inwhich the reverse range pressure acts on the spool in the direction ofthe fail position. Thus, the first switching valve is locked in thenormal position when the signal pressure of the signal pressure outputsolenoid valve is output, and even during a failure, it is possible toswitch the first switching valve to the fail position due to the reverserange pressure.

According to a third aspect of the present invention, because a secondswitching valve is provided that is switched from a first position to asecond position when the signal pressure of the signal pressure outputsolenoid valve is output, and is locked in the first position when thereverse range pressure is input, while hydraulic control that uses thesignal pressure output solenoid valve in the reverse range is enabled,it is possible to output the signal pressure of the signal pressureoutput solenoid valve in the reverse range in order to establish thereverse speed.

According to a fourth aspect of the present invention, because thesecond switching valve is a valve that outputs a lock-up clutchengagement pressure in order to engage the lock-up clutch in the secondposition, in the forward range, it is possible to carry out hydrauliccontrol of the lock-up clutch by using the signal pressure outputsolenoid valve.

According to a fifth aspect of the present invention, during a failurein which the range position of the range switching valve is not detectedby the range position detecting device, forward start control, in whichthe second engagement pressure control solenoid valve is energized, iscarried out, and thus when the range switching valve is in the reverserange position, the forward speed is established, and it is possible forthe vehicle to travel forward. In addition, when the range switchingvalve is in the reverse range position, while the second engagementpressure is not output from the second engagement pressure controlsolenoid valve when the reverse range pressure is not output and theestablishment of the forward speed could be obstructed, the firstswitching valve is switched to the fail position by the reverse rangepressure, it is possible to establish the reverse speed by supplying thereverse range pressure to the first hydraulic servo, and it is possiblefor the vehicle to travel in reverse.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a skeleton drawing showing the automatic transmission that canbe used in an exemplary embodiment of the present invention;

FIG. 2 is an operating table for an exemplary embodiment of the presentautomatic transmission;

FIG. 3 is a velocity diagram for an exemplary embodiment of the presentautomatic transmission;

FIG. 4 is a schematic drawing showing the overall hydraulic controlapparatus according to an exemplary embodiment of the present invention;

FIG. 5 is a partial diagram showing the forward speed change functionportion in the hydraulic control apparatus according to an exemplaryembodiment of the present invention;

FIG. 6 is a partial diagram showing the simultaneous engagementprevention function portion in the hydraulic control apparatus accordingto an exemplary embodiment of the present invention; and

FIG. 7 is a partial diagram showing the reverse speed change functionportion in the hydraulic control apparatus according to an exemplaryembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, exemplary embodiments of the present invention will be explainedwith reference to FIG. 1 through FIG. 7.

Configuration of Automatic Transmission

First, a schematic structure of the staged automatic transmission(below, referred to simply as an “automatic transmission”) in which anexemplary embodiment of the present invention can be applied will beexplained with reference to FIG. 1. As shown in FIG. 1, a preferableautomatic transmission 1 that is used, for example, in an FR type (frontengine, rear drive) vehicle has an input shaft 11 for the automatictransmission 1 that is able to connect to an engine (not illustrated),and is provided with a torque converter 7 that is disposedconcentrically with the input shaft 11 in the axial direction and aspeed change mechanism 2.

The torque converter 7 has a pump impeller 7 a that is connected to theinput shaft 11 of the automatic transmission 1 and a turbine runner 7 bto which the rotation of the pump impeller 7 a is transmitted via aworking liquid. The turbine runner 7 b is connected to the input shaft12 of the speed change mechanism 2 disposed coaxially to the input shaft11. In addition, the torque converter 7 is provided with a lock-upclutch 10, and when the lock-up clutch 10 is engaged by the hydrauliccontrol of the hydraulic control apparatus described below, the rotationof the input shaft 11 of the automatic transmission 1 described above isdirectly transmitted to the input shaft 12 of the speed change mechanism2.

This speed change mechanism 2 is provided with a planetary gear DP and aplanetary gear unit PU on the input shaft 12 (and the intermediate shaft13). This planetary gear DP is provided with a sun gear S1, a carrierCR1, and a ring gear R1. In the carrier CR1, a pinion P1 that mesheswith the sun gear S1 and a pinion P2 that meshes with the ring gear R1mesh together to form what is referred to as a double pinion planetarygear.

In addition, the planetary gear unit PU has four rotating elements: asun gear S2, a sun gear S3, a carrier CR2 (CR3), and a ring gear R3(R2), and in the carrier CR2, a long pinion P4 that meshes with the sungear S2 and a ring gear R3 and a short pinion P3 that meshes with thelong pinion P4 and the sun gear S3 mesh together to form what isreferred to as a Ravigneaux-type planetary gear.

The rotation of the sun gear S1 of the planetary gear DP described aboveis held stationary by being connected to a boss portion 3 b that isintegrally attached, for example, to the transmission case 3. Inaddition, the carrier CR1 described above is connected to the inputshaft 12 to rotate together with the rotation of the input shaft 12(below, referred to as “input rotation”), and at the same time isconnected to the fourth clutch C-4 (first friction engagement element).Furthermore, the ring gear R1 provides a reduced rotation in which theinput rotation is reduced due to the stationary sun gear S1 and thecarrier CR1 that provides the input rotation, and at the same time ismoconnected to a first clutch C-1 (second friction engagement element)and a third clutch C-3 (a friction engagement element).

The sun gear S2 of the planetary gear unit PU described above is able tofasten freely to the transmission case 3 by connecting to the firstbrake B-1 (a friction engagement element), which serves as a lockingdevice, and at the same time, connects to the fourth clutch C-4 and thethird clutch C-3. The input rotation of the carrier CR1 via the fourthclutch C-4 and the reduced rotation of the ring gear R1 via the thirdclutch C-3 can each be freely and separately input. In addition, the sungear S3 is connected to the first clutch C-1 and the reduced rotation ofthe ring gear R1 can be freely input.

Furthermore, the carrier CR2 is connected to the second clutch C-2 (afriction engagement element), to which the rotation of the input shaft12 is input via the intermediate shaft 13, and the input rotation can befreely input via the second clutch C-2. In addition, the carrier CR2 isconnected to the one-way clutch F-1 and the second brake B-2 (a frictionengagement element), which serve as locking devices, the one-way clutchF-1 restricts the rotation in one direction with respect to thetransmission case 3, and the rotation can be held stationary orpermitted by the second brake B-2. In addition, the ring gear R3 isconnected to the output shaft 15, which outputs a rotation to thevehicle's driven wheels (not illustrated).

Transmission Path of Each Shift Speed

Next, based on the configuration described above, the operation of thespeed change mechanism 2 will be explained with reference to FIG. 1,FIG. 2, and FIG. 3. Note that in the velocity diagram shown in FIG. 3,the vertical axes show the rotation of the respective rotation elements(each gear), and the horizontal axes show the correspondence with thegear ratios of these rotation elements. In addition, in the part of thevelocity diagrams showing the planetary gear DP, the vertical axis thatis the closest to the end in the transverse direction (the left side inFIG. 3) corresponds to the sun gear S1 and the vertical axes in sequencetowards the right side of the figure correspond to the ring gear R1 andthe carrier CR1. Furthermore, in the part of the velocity diagramshowing the planetary gear unit PU, the vertical axis that is closest tothe end in the transverse direction (the right side in FIG. 3)corresponds to the sun gear S3, and the vertical axes in sequencetowards the left side of the figure correspond to the ring gear R3 (R2),the carrier CR2 (CR3), and the sun gear S2.

In the D (drive) range, for example, while being driven by the engine(drive source) in the first forward speed (1st), as shown in FIG. 2, thefirst clutch C-1 and the one-way clutch F-1 are engaged. Thus, as shownin FIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotationis reduced by the stationary sun gear S1 and by the carrier CR1, whichis the input rotation, is input to the sun gear S3 via the first clutchC-1. In addition, the rotation of the carrier CR2 is restricted to onedirection (the normal rotation direction), or specifically, the rotationof the carrier CR2 is held stationary by preventing the reverse rotationof the carrier CR2. Thus, the reduced rotation input to the sun gear S3is output to the ring gear R3 via the stationary carrier CR2, and anormal rotation is output from the output shaft 15 as the first forwardspeed.

Note that while not driving in the first forward speed (1st),specifically, during engine braking (during coasting), the carrier CR2is held stationary by being locked by the second brake B-2, and thus thenormal rotation of the carrier CR2 is prevented. Thereby, the state ofthe first forward speed is maintained. In addition, while driving in thefirst forward speed, because the reverse rotation of the carrier CR2 isprevented by the one-way clutch F-1 and normal rotation is possible,attaining the first forward speed when, for example, switching from anon-traveling range to a traveling range, can be carried out smoothly bythe automatic engagement of the one-way clutch F-1.

In the second forward speed (2nd), as shown in FIG. 2, the first clutchC-1 is engaged, and the first brake B-1 is locked. Thus, as shown inFIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation isreduced by the stationary sun gear S1 and by the carrier CR1, which isthe input rotation, is input to the sun gear S3 via the first clutchC-1. In addition, the rotation of the sun gear S2 is held stationary bythe locking of the first brake B-1. Thus, the carrier CR2 acquires areduced rotation that is lower than that of the sun gear S3, the reducedrotation that is input to the sun gear S3 is then input to the ring gearR3 via the carrier CR2, and the normal rotation is output from theoutput shaft 15 as the second forward speed.

In the third forward speed (3rd), as shown in FIG. 2, the first clutchC-1 and the third clutch C-3 are engaged. Thus, as shown in FIG. 1 andFIG. 3, the rotation of the ring gear R1, whose rotation is reduced bythe stationary sun gear S1 and by the carrier CR1, which is the inputrotation, is input to the sun gear S3 via the first clutch C-1. Inaddition, the reduced rotation of the ring gear R1 is input to the sungear S2 by the engagement of the third clutch C-3. That is, because thereduced rotation of the ring gear R1 is input to the sun gear S2 and thesun gear S3, the planetary gear unit PU becomes directly linked to thereduced rotation, the reduced rotation is input directly into the ringgear R3, and the normal rotation is output from the output shaft 15 asthe third forward speed.

In the fourth forward speed (4th), as shown in FIG. 2, the first clutchC-1 and the fourth clutch C-4 are engaged. Thus, as shown in FIG. 1 andFIG. 3, the rotation of the ring gear R1, whose rotation is reduced bythe stationary sun gear S1 and by the carrier CR1, which is the inputrotation, is input to the sun gear S3 via the first clutch C-1. Inaddition, the input rotation of the carrier CR1 is input to the sun gearS2 due to the engagement with the fourth clutch C-4. Thus, the carrierCR2 acquires a reduced rotation that is higher than that of the sun gearS3, the reduced rotation that is input by the sun gear S3 is then outputto the ring gear R3 via the carrier CR2, and the normal rotation isoutput from the output shaft 15 as the fourth forward speed.

In the fifth forward speed (5th), as shown in FIG. 2, the first clutchC-1 and the second clutch C-2 are engaged. Thus, as shown in FIG. 1 andFIG. 3, the rotation of the ring gear R1, whose rotation is reduced bythe stationary sun gear S1 and by the carrier CR1, which is the inputrotation, is input to the sun gear S3 via the first clutch C-1. Inaddition, the input rotation is input to the carrier CR2 due to theengagement with the second clutch C-2. Thus, a reduced rotation that ishigher than that of the fourth forward speed described above due to thereduced rotation input to the sun gear S2 and the input rotation inputto the carrier CR2, is output to the ring gear R3, and the normalrotation is output from the output shaft 15 as the fifth forward speed.

In the sixth forward speed (6th), as shown in FIG. 2, the second clutchC-2 and the fourth clutch C-4 are engaged. Thus, as shown in FIG. 1 andFIG. 3, the input rotation of the carrier CR1 is input to the sun gearS2 due to the engagement with the fourth clutch C-4. In addition, theinput rotation of the carrier CR2 is input due to the engagement withthe second clutch C-2. That is, because the input rotation is input tothe sun gear S2 and to the carrier CR2, the planetary gear unit PU iscoupled directly to the input rotation, the input rotation is outputdirectly to the ring gear R3, and the normal rotation is output from theoutput shaft 15 as the sixth forward speed.

In the seventh forward speed (7th, OD1), as shown in FIG. 2, the secondclutch C-2 and the third clutch C-3 are engaged. Thus, as shown in FIG.1 and FIG. 3, the rotation of the ring gear R1, whose rotation isreduced by the stationary sun gear S1 and by the carrier CR1, which isthe input rotation, is input to the sun gear S2 via the third clutchC-3. In addition, the input rotation is input to the carrier CR2 due tothe engagement with the second clutch C-2 via the third clutch C-3.Thus, an increased rotation that is slightly higher than the inputrotation due to the reduced rotation that is input to the sun gear S2and the input rotation that is input to the carrier CR2 is output to thering gear R3, and the normal rotation is output from the output shaft 15as the seventh forward speed (the first overdrive speed, which is fasterthan the directly coupled speed).

In the eighth forward speed (8th, OD2), as shown in FIG. 2, the secondclutch C-2 is engaged, and the first brake B-1 is locked. Thus, as shownin FIG. 1 and FIG. 3, the input rotation is input to the carrier CR2 dueto the engagement with the second clutch C-2. In addition, the rotationof the sun gear S2 is held stationary due to the locking of the firstbrake B-1. Thus, the input rotation of the carrier CR2 by the stationarysun gear S2 becomes an increased rotation that is higher than that ofthe seventh forward speed described above, this rotation is input to thering gear R3, and the normal rotation is output from the output shaft 15as the eighth forward speed (the second overdrive speed), which isfaster than the directly coupling speed.

In the first reverse speed (Rev1), as shown in FIG. 2, the third clutchC-3 is engaged, and the second brake B-2 is locked. Thus, as shown inFIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation isreduced by the stationary sun gear S1 and by the carrier CR1, which isthe input rotation, is input to the sun gear S2 via the third clutchC-3. In addition, the rotation of the carrier CR2 is held stationary bybeing locked by the second brake B-2. Thus, the reduced rotation that isinput to the sun gear S3 is output to the ring gear R3 via thestationary carrier CR2, and the reverse rotation is output from theoutput shaft 15 as the first reverse speed.

In the second reverse speed (Rev2), as shown in FIG. 2, the fourthclutch C-4 is engaged, and the second brake B-2 is locked. Thus, asshown in FIG. 1 and FIG. 3, the input rotation of the carrier CR1 due tothe engagement with the clutch C-4 is input to the sun gear S2. Inaddition, the rotation of the carrier CR2 is held stationary by beinglocked by the second brake B-2. Thus, the input rotation that is inputto the sun gear S2 is output to the ring gear R3 via the stationarycarrier CR2, and the reverse rotation is output from the output shaft 15as the second reverse speed.

Note that in an exemplary embodiment of the present automatictransmission, the fourth clutch C-4 and the second brake B-2 are engagedwhile in the reverse range due to the hydraulic control by the hydrauliccontrol apparatus 20 that will be described in detail below, and thus,only a second reverse speed is established. However, this can bemodified in various manners, and only a first reverse speed or both afirst reverse speed and a second reverse speed may be established.

In addition, in the P (parking) range and the N (neutral) range, thefirst clutch C-1, the second clutch C-2, the third clutch C-3, and thefourth clutch C-4 are released. Thereby, the carrier CR1 and the sungear S2 are disengaged. In addition, the ring gear R1, the sun gear S2,and the sun gear S3 are disengaged, and thereby the planetary gear DPand the planetary gear unit PU are disengaged. Additionally, the inputshaft 12 (intermediate shaft 13) and the carrier CR2 are disengaged.Thereby, the transfer of the driving force between the input shaft 12and the planetary gear unit PU is disengaged, and thus, the transfer ofthe driving force between the input shaft 12 and the output shaft 15 isdisengaged.

Overall Configuration of Hydraulic Control Apparatus

Next, the hydraulic control apparatus 20 of the automatic transmissionaccording to an exemplary embodiment of the present invention will beexplained. First, the overall hydraulic control apparatus 20 will bebroadly explained with reference to FIG. 4. Note that in the presentexemplary embodiment, there is one spool in each valve, and in order toexplain the spool's switching position and the control position, thestate in the right half portion shown in FIG. 4 through FIG. 7 isreferred to as the “right half position” and the state in the left halfportion shown therein is referred to as the “left half position”.

As shown in FIG. 4, generally in order to regulate and generate oilpressures that provide the various types of primary pressures, thehydraulic control apparatus 20 is provided with a strainer 22, an oilpump 21, a manual shift valve (range switching valve) 23, a primaryregulator valve 25, a secondary regulator valve 26, a solenoid modulatorvalve 27, and a linear solenoid valve SLT (not illustrated).

In addition, in order to selectively switch or regulate the oilpressures in each of the oil paths based on the various types of primarypressures, the hydraulic control apparatus 20 is provided with valveswhose spool positions are switched and controlled. These valves includea lock-up relay valve (second switching valve) 31, a second clutch applyrelay valve (third switching valve) 32, a lock pressure delay valve 33,a first clutch apply relay valve (first switching valve) 34, a B-2 applycontrol valve (second switching valve) 35, a B-2 control valve 36, a B-2check valve 37, a first clutch apply control valve 41, a signal checkvalve 42, a second clutch apply control valve 43, a B-1 apply controlvalve 44, a C-4 relay valve 45 (first switching valve), and the like.

Furthermore, in order to electrically control and supply oil pressure toeach type of relay valve and each type of control valve described above,the hydraulic control apparatus 20 is provided with a linear solenoidvalve SL1, a linear solenoid valve SL2, a linear solenoid valve SL3, alinear solenoid valve SL4, a linear solenoid valve SL5, a linearsolenoid valve SLU, a solenoid valve SR, and a solenoid valve (failsolenoid valve) SL.

Note that the solenoid valves other than the solenoid valve SR in thehydraulic control apparatus 20, or specifically, the linear solenoidvalves SL1 to SL5, SLU, and the solenoid valve SL interrupt the inputport and the output port while de-energized (below, referred to as being“off”), and communicate the same while energized (below, referred to asbeing “on”). In other words, what is termed a normally closed (N/C) typevalve is used. In contrast, a normally open (N/O) type valve is usedonly in the solenoid valve SR.

In addition, the hydraulic control apparatus 20 is provided with ahydraulic servo 51 that can engage and disengage the first clutch C-1, ahydraulic servo 52 that can engage and disengage the second clutch C-2,a hydraulic servo 53 that can engage and disengage the third clutch C-3,a hydraulic servo 54 that can engage and disengage the fourth clutchC-4, a hydraulic servo 61 that can engage and disengage the first brakeB-1, and a hydraulic servo 62 that can engage and disengage the secondbrake B-2. The engagement between the clutches and the hydraulic servosis based on the engagement pressures that are regulated and are suppliedby the types of valves described above.

Next, the portions in the hydraulic control apparatus 20 that generateeach type of primary pressure described above, that is, the linepressure, secondary pressure, and the modulator pressure, will beexplained. Note that the portions that generate the line pressure, thesecondary pressure, and the modulator pressure are identical to those ofa common hydraulic control apparatus for an automatic transmission, andthey are well-known. Thus, the explanation thereof will be brief.

The oil pump 21 generates oil pressure, for example, by being connectedto and rotated by the pump impellor 7 a of the torque converter 7described above or being connected to and driven by the rotation of theengine, and drawing oil from an oil pan (not illustrated) through thestrainer 22. In addition, the hydraulic control apparatus 20 is providedwith a linear solenoid valve SLT (not illustrated), and this linearsolenoid valve SLT uses the modulator pressure P_(MOD) regulated by thesolenoid modulator valve 27 described below as a primary pressure andregulates and outputs a signal pressure P_(SLT) that depends on thethrottle opening degree.

The primary regulator valve 25 regulates the oil pressure generated bythe oil pump 21 so as to attain a line pressure P_(L) by discharging aportion thereof based on a signal pressure P_(SLT) of the linearsolenoid valve SLT that is input to the spool having applied thereto theurging force of the spring of the primary regulator valve 25. This linepressure P_(L) is supplied to a manual shift valve 23, a solenoidmodulator valve 27, the clutch apply relay valve 32, the linear solenoidvalve SL5, the first clutch apply control valve 41, a second clutchapply control valve 43, and a B-1 apply control valve 44, as describedbelow.

In addition, the oil pressure discharged by the primal regulator valve25 is regulated so as to attain a secondary pressure P_(SEC) bydischarging a portion thereof based on the signal pressure P_(SLT) ofthe linear solenoid valve SLT described above that is input to the spoolhaving the urging force of the spring of the secondary regulator valve26 applied thereto by the secondary regulator valve 26. This secondarypressure P_(SEC) is supplied to a lubricating oil path and the like (notillustrated), and at the same time is supplied to the lock-up relayvalve 31 and used as the primary pressure for the control of the lock-upclutch 10.

In addition, the solenoid modulator valve 27 regulates the line pressureP_(L), which is regulated by the primary regulator valve 25, so as toattain respectively constant modulator pressures P_(MOD) when the linepressure P_(L) is equal to or greater than a prescribed pressure due tothe urging force of the spring of the solenoid modulator valve 27. Thesemodulator pressures P_(MOD) are supplied as primary pressures to thelinear solenoid valve SLT (not illustrated), the solenoid valve LS(normally closed), the solenoid valve SR (normally open), and the linearsolenoid valve SLU (normally closed).

Configuration of Forward Shifting Function Portion in Hydraulic ControlApparatus

Next, the functional portion that mainly carries out the forwardshifting control in the hydraulic control apparatus 20 according to anexemplary embodiment of the present invention will be explained withreference to FIG. 5. First, the manual shift valve 23 has a spool 23 pthat is mechanically (or electrically) driven by a shift lever that isprovided at the driver's seat (not illustrated), and the line pressureP_(L) described above is input to the input port 23 a. When the shiftposition is set to the D (drive) range based on the operation of a shiftlever, the input port 23 a and the output port 23 b communicate based onthe position of the spool 23 p, and the forward (D) range pressure P_(D)is output from the output port 23 b with the line pressure P_(L) servingas the primary pressure.

The output ports 23 b and 23 c are connected to the input port SL1 a ofthe linear solenoid valve SL1, the input port SL3 a of the linearsolenoid valve SL3, the input port 34 k of the first clutch apply relayvalve 34, and the input port 35 d of the B-2 apply control valve 35,which will be explained in detail below, and when driving in the forwardrange, the forward range pressure P_(D) is output to these ports.

In addition, when the shift position is set to the R (reverse) rangebased on the operation of the shift lever, the input port 23 a and theoutput port 23 d communicate based on the position of the spool 23 p,and the reverse (R) range pressure P_(R) is output by the output port 23d, where the line pressure P_(L) serves as the primary pressure for thereverse (R) range pressure P_(R).

The output port 23 d is connected to the input port 34 i of the firstclutch apply relay valve 34 and the input port 36 d of the B-2 controlvalve 36, which will be explained in detail below, and while driving inthe forward range, the reverse range pressure P_(R) is output to theseports.

Note that when the P (parking) range or the N (neutral) range(non-traveling range) has been set based on the operation of the shiftlever, the input port 23 a and the output ports 23 b, 23 c, and 23 d areinterrupted by the spool 23 p, and thus the range pressure is notoutput.

The solenoid valve SR inputs a modulator pressure P_(MOD) to the inputport Sa (shared with the solenoid valve SL). During normal operation(except during engine braking in the first forward speed describedbelow), the solenoid valve SR becomes energized and does not output asignal pressure P_(SR) from the output port SRb. The solenoid valve SRoutputs a signal pressure P_(SR) from the output port SRb whilede-energized, for example, during engine braking in the first forwardspeed or during the all-solenoids-off mode described below (refer toFIG. 2). When the output port SRb is connected to the oil chamber 32 aof the second clutch apply relay valve 32, the oil chamber 34 a of thefirst clutch apply relay valve 34, and the input port 34 b, and turnedoff, the signal pressure P_(SR) is output to the oil chamber and theports, and as will be explained in detail below, when the first clutchapply relay valve 34 is locked at the right half position, the signalpressure P_(SR) is also output to the oil chamber 35 a of the B-2 applycontrol valve 35.

The linear solenoid valve SLU inputs the modulator pressure P_(MOD) tothe input port SLUa, and while energized, outputs the signal pressureP_(SLU) from the output port SLUb (refer to FIG. 2). The output portSLUb is connected to the oil chamber 36 a of the B-2 control valve 36via the lock-up relay valve 31, and outputs the signal pressure P_(SLU)to this oil chamber 36 a when the lock-up relay valve 31 is in the righthalf position (refer to FIG. 4 and FIG. 7).

The linear solenoid valve (the second engagement pressure controlsolenoid valve) SL1 includes an input port SL1 a that inputs a forwardrange pressure P_(D), an output port SL1 b that regulates and outputsthe forward range pressure P_(D) as an engagement pressure (secondengagement pressure) P_(C1) to the hydraulic servo (second hydraulicservo) 51 when energized, a feedback port SL 1 c, and a discharge portSL1 d mainly for draining the engagement pressure P_(C1) of thehydraulic servo 51. The discharge port SL1 d is connected to a port 32 fof the second clutch apply relay valve 32 described below, and duringnormal operation, the engagement pressure P_(C1) is drained by the drainport EX of the second clutch apply relay valve 32. Note that the outputport SL1 b is connected to the hydraulic servo 51 via the first clutchapply control valve 41 described below (refer to FIG. 4 and FIG. 6).

The linear solenoid valve SL2 includes an input port SL2 a that inputsthe forward range pressure P_(D) via the B-2 apply control valve 35described below, an output port SL2 b that regulates and outputs theforward range pressure P_(D) to the hydraulic servo 52 as the engagementpressure P_(C2) when energized, a feedback port SL2 c, and a dischargeport SL2 d mainly for discharging the engagement pressure P_(C2) of thehydraulic servo 52. During normal operation, the discharge port SL2 dcommunicates with the port 32 d and port 32 e of the second clutch applyrelay valve 32, the port 34 d of the first clutch apply relay valve 34,and the drain port EX, and the engagement pressure P_(C2) is drained bythe drain port EX.

The linear solenoid valve SL3 includes an input port SL3 a that inputsthe forward range pressure P_(D), an output port SL3 b that regulatesand outputs the forward range pressure P_(D) to the hydraulic servo 53as the engagement pressure P_(C3) when energized, a feedback port SL3 c,and a discharge port SL3 d mainly for discharging the engagementpressure P_(C3) of the hydraulic servo 53. The discharge port SL3 d isconnected to the port 34 e of the first clutch apply relay valve 34described below, and during normal operation, the engagement pressureP_(C3) is drained by the drain port EX of the first clutch apply relayvalve 34.

The linear solenoid valve (first engagement pressure control valve) SL4includes an input port SL4 a that inputs the line pressure P_(L) (lockpressure) that is fed through the second clutch apply relay valve 32 tobe described below, an output port SL4 b that regulates and outputs theline pressure P_(L) to the hydraulic servo (first hydraulic servo) 54 asthe engagement pressure (first engagement pressure) P_(C4) whenenergized, a feedback port SL4 c, and a drain port EX that drains theengagement pressure P_(C4) of the hydraulic servo 54. Note that theoutput port SL4 b is connected to the hydraulic servo 54 via the C-4relay valve 45 and the second clutch apply control valve 43 (refer toFIG. 4, FIG. 6, and FIG. 7).

The linear solenoid valve (the engagement pressure control solenoidvalve) SL5 includes an input port SL5 a that inputs the line pressureP_(L), an output port SL5 b that regulates and outputs the line pressureP_(L) to the hydraulic servo 61 as the engagement pressure P_(B1) whenenergized, a feedback port SL5 c, and a drain port EX that drains theengagement pressure P_(B1) of the hydraulic servo 61. Note that theoutput port SL5 b is connected to the hydraulic servo 61 via the B-1apply control valve 44, which will be described below (refer to FIG. 4and FIG. 6).

The B-2 apply control valve 35 includes a spool 35 p, a spring 35 s thaturges the spool 35 p upward in the figure, and in addition, above thespool 35 p in the figure, includes an oil chamber 35 a, an input port 35b, an output port 35 c, an input port 35 d, an output port 35 e, and anoil chamber 35 f. The spool 35 p of the B-2 apply control valve 35 isset in the right half position when the signal pressure P_(SR) is inputto the oil chamber 35 a, and otherwise, is set in the left half positiondue to the urging force of the spring 35 s. In addition, the spool 35 pis fastened in the left half position irrespective of the input of thesignal pressure P_(SR) when any of the engagement pressures P_(C3),P_(C4), and P_(B1) described below is input to the oil chamber 35 f

The forward range pressure P_(D) is input to the input port 35 d and theoutput port 35 e is connected to the input port SL2 a of the linearsolenoid valve SL2. When the spool 35 p is in the left half position,the forward range pressure P_(D) is output to the linear solenoid valveSL2. In addition, the output port 35 c is connected to the input port 36c of the B-2 control valve 36 described below, and when the signalpressure P_(SR) is input to the oil chamber 35 a and the spool 35 p isat the right half position, the forward range pressure P_(D) is outputto the hydraulic servo 62 via the B-2 control valve 36.

The B-2 control valve 36 includes a spool 36 p and a spring 36 s thaturges this spool 36 b upward in the figure, and in addition, above thespool 36 p in the figure, includes an oil chamber 36 a, an output port36 b, an input port 36 c, an input port 36 d, an output port 36 e, and afeedback oil chamber 36 f. The spool 36 p of the B-2 apply control valve36 is controlled so as to move from the right half position to the lefthalf position when the signal pressure P_(SLU) is input to the oilchamber 36 a.

When driving in the forward range (the first forward speed during enginebraking), the forward range pressure P_(D) is input to the input port 36c via the B-2 apply control valve 35, and the engagement pressure P_(B2)is regulated and output by the output port 36 b based on the signalpressure P_(SLU) of the oil chamber 36 a and the feedback pressure ofthe oil chamber 36 f. In addition, while driving in the reverse range,the reverse range pressure P_(R) is input to the port 36 d by the manualshift valve 23, and the engagement pressure P_(B2) is output by theoutput port 36 e.

The B-2 check valve 37 includes an input port 37 a, an input port 37 b,and an output port 37 c, and one of either the oil pressure input to theinput port 37 a or the input port 37 b is output by the output port 37c. Specifically, when the engagement pressure P_(B2) is input to theinput port 37 a from the output port 36 b of the B-2 control valve 36,this engagement pressure P_(B2) is then output to the hydraulic servo 62from the output port 37 c. When the engagement pressure P_(B2) is inputto the input port 37 b from the output port 36 c of the B-2 controlvalve 36, this engagement pressure P_(B2) is then output to thehydraulic servo 62 from the output port 37 c.

The first clutch apply relay valve 34 includes a spool 34 and a spring34 s that urges the spool 34 p upward in the figure, and above the spool34 p in the figure, also includes an oil chamber 34 a, an input port 34b, an output port 34 c, an output port 34 d, an output port 34 e, aninput port 34 k, an input port 34 f, an output port 34 g, and an oilchamber 34 j.

In the oil chamber 34 a, during normal operation (excluding enginebraking in the first forward speed), when the solenoid valve SR isturned on, the signal pressure P_(SR) is not input, and due to theurging force of the spring 34 s, the spool 34 p is set in the right halfposition. In addition, when the spool 34 p is in the right halfposition, the engagement pressure P_(C1) is input from the linearsolenoid valve SL1 to the input port 34 f, the engagement pressureP_(C1) is output to the oil chamber 34 j from the output port 34 g, andthe spool 34 p is locked in the right half position.

While the spool 34 p is in the right half position, the forward rangepressure P_(D) that is input to the input port 34 k and the reverserange pressure P_(R) that is input to the input port 34 i areinterrupted. In addition, when the spool 34 p is locked in the righthalf position by the engagement pressure P_(C1), the spool 34 p ismaintained in the right half position even when the signal pressureP_(SR) is input to the oil chamber 34 a, and the signal pressure P_(SR)that is input to the input port 34 b is output to the oil chamber 35 aof the B-2 apply control valve 35 from the output port 34 c. Inaddition, the output port 34 d and the output port 34 e are connected tothe discharge port SL3 d of the linear solenoid valve SL3 and dischargeport SL2 d of the linear solenoid valve SL2 via the second clutch applyrelay valve 32, which will be described below. When the engagementpressure P_(C3) is discharged by the linear solenoid valve SL3 and theengagement pressure P_(C2) is discharged by the linear solenoid valveSL2, the engagement pressure P_(C3) and the engagement pressure P_(C2)are input to and drained by the drain port EX.

In contrast, during the all-solenoids-off mode, which will be describedin detail below, the signal pressure P_(SR) is input to the oil chamber34 a, the engagement pressure P_(C1) from the linear solenoid valve SL1is interrupted, and the spool 34 p is set to the left half position.When this spool 34 p is in the left half position, in the forward range,the forward range pressure P_(D) that is input to the input port 34 k isoutput from the output port 34 d and the output port 34 e, and is thenoutput as fail engagement pressure to the discharge port SL3 d of thelinear solenoid valve SL3 and the input port 34 e of the second clutchapply relay valve 32, which will be explained below. In addition, in thereverse range, the reverse range pressure P_(R) that is input to theinput port 34 i is output to the input port 35 b of the B-2 applycontrol valve 35 from the output port 34 h, and this reverse rangepressure P_(R) is output to the input port 36 c of the B-2 control valve36 via the B-2 apply control valve 35, which is in the left halfposition, without the signal pressure P_(SR) being input to the oilchamber 35 a. Thereby, as described above, even when the B-2 controlvalve 36 sticks, locks in the left half position, and the communicationbetween the input port 36 d and the output port 36 e is interrupted, thereverse range pressure P_(R) is reliably supplied to the hydraulic servo62 by the communication between the input ports 36 c and 36 b.

The second clutch apply relay valve 32 includes a spool 32 p, a spring32 s that urges the spool 32 p upward in the figure, and above the spool32 p in the figure, also includes an oil chamber 32 a, an input port 32b, an output port 32 c, an output port 32 d, an input port 32 e, aninput port 32 f, and an oil chamber 32 g. In addition, a lock pressuredelay valve 33, which has a spool 33 p that can abut and press againstthe spool 32 p, is integrally provided at the bottom of the secondclutch apply relay valve 32. The lock pressure delay valve 33 includes aspool 33 p and a spring 33 s that urges this spool 33 p upward in thefigure, and also includes an oil chamber 33 a in which the oil pressureacts so as to press the spool 33 p downward in the figure and an inputport 33 b that communicates with the oil chamber 32 g of the secondclutch apply relay valve 32. In addition, orifices 71 and 72 areprovided in the oil duct that connects the output port 32 d of thesecond clutch apply relay valve 32 and the input port 33 b of the lockpressure delay valve 33.

During normal operation (and during the all-solenoids-off mode while theengine is starting up as described below), the spool 32 p of the secondclutch apply relay valve 32 is set at the right half position due to theurging force of the spring 32 s and the spring 33 s. When the spool 32 pis in the right half position, the line pressure P_(L) that is input tothe input port 32 b is input to the input port SL4 a of the linearsolenoid valve SL4 from the output port 32 c and to the oil chamber 33 aand the input port 33 b of the lock pressure delay valve 33, and thelock pressure delay valve 33 is locked in the left half position due tothe oil pressure of the oil chamber 33 a. As a result, because the oilchamber 33 b and the oil chamber 32 g communicate, the oil pressure fromthe oil chamber 33 b is supplied to the oil chamber 32 g, and the spool32 p is locked in the right half position.

In addition, when this spool 32 p is in the right half position, theoutput port 32 f is connected to the discharge port SL1 d of the linearsolenoid valve SL1, and when the engagement pressure P_(C1) isdischarged by this linear solenoid valve SL1, the engagement pressureP_(C1) is input and drained from the drain port EX. Furthermore, theoutput port 32 d is connected to the discharge port SL2 d of the linearsolenoid valve SL2, and at the same time, the input port 32 e isconnected to the output ports 34 d and 34 e of the first clutch applyrelay valve 34. When the engagement pressure P_(C2) is discharged fromthe linear solenoid valve SL2, the engagement pressure P_(C2) is inputfrom the output port 32 d and is drained from the drain port EX of thefirst clutch apply relay valve 34 via the input port 32 e.

In contrast, after the engine start-up during the all-solenoids-offmode, which will be described in detail below, the spool 32 p is in theleft half position, the line pressure P_(L) that is input to the inputport 32 b is interrupted, and then the input port 32 e and the outputport 32 f communicate.

Operation of Each Forward Shift Speed

In the hydraulic control apparatus 20 having the functional portionsthat carry out the forward shift control described above, in the firstforward speed while driving in the forward range, the linear solenoidvalve SL1 is turned on, the forward range pressure P_(D) that is inputto the input port SL1 a is regulated and output to the hydraulic servo51 as the engagement pressure P_(C1), and the first clutch C-1 isengaged. Thereby, coupled with the locking of the one-way clutch F-1,the first forward speed is attained.

In addition, while using engine braking in the first forward speed, thesolenoid valve SR is turned off and the signal pressure P_(SR) is outputfrom the output port SRb. At this time, the second clutch apply relayvalve 32 is locked at the right half position by the line pressureP_(L), and the first clutch apply relay valve 34 is locked at the righthalf position by the engagement pressure P_(C1). Thus, the signalpressure P_(SR) of the solenoid valve SR is input to the oil chamber 35a of the B-2 apply control valve 35, the forward range pressure P_(D) ofthe input port 35 b is input to the input port 36 c of the B-2 controlvalve 36 from the output port 35 c, and the spool 36 p is controlled bythe signal pressure P_(SLU) of the linear solenoid valve SLU. Thus, theforward range pressure P_(D) is regulated and output to the hydraulicservo 62 via the B-2 check valve 37 as engagement pressure P_(B2), andthe second brake B-2 is locked. Thereby, coupled with the engagement ofthe first clutch C-1, the engine brake in the first forward speed isattained.

In the second forward speed, in addition to the linear solenoid valveSL1 being turned on, the linear solenoid valve SL5 is turned on, theline pressure P_(L) that is input to the input port SL5 a is regulatedand output to the hydraulic servo 61 as the engagement pressure P_(B1),and the first brake B-1 is engaged. Thereby, coupled with the engagementof the first clutch C-1, the second forward speed is attained.

Note that in the forward range, in the neutral control (N cont) whichenhances the fuel economy by releasing the first clutch C-1, controlthat is similar to that of the second forward speed is carried out, andthe linear solenoid valve SL1 regulates the engagement pressure P_(C1)such that the first clutch C-1 remains just prior to engaging (a statein which the rotational play has been reduced). Thereby, the neutralstate is set such that, the second forward speed is formed immediatelyafter the neutral control (N cont) is released.

In the third forward speed, in addition to the linear solenoid valve SL1being turned on, the linear solenoid valve SL3 is turned on, the forwardrange pressure P_(D) that is input to the input port SL3 a is regulatedand output to the hydraulic servo 53 as the engagement pressure P_(C3),and the third clutch C-3 is engaged. Thereby, coupled with theengagement of the first clutch C-1, the third forward speed is attained.

In the fourth forward speed, in addition to the linear solenoid valveSL1 being turned on, the linear solenoid valve SL4 is turned on, theline pressure P_(L) that is input to the input port SL4 a via the secondclutch apply relay valve 32 is regulated and output to the hydraulicservo 54 as engagement pressure P_(C4), and the fourth clutch C-4 isengaged. Thereby, coupled with the engagement of the first clutch C-1,the fourth forward speed is attained.

Note that, in the worst case, when the fourth forward speed is notattained, a state may have occurred in which the line pressure P_(L) isnot input to the input port SL4 a because the second clutch apply relayvalve 32 is stuck in the left half position, and thus the fourth clutchC-4 is not engaged, and the transition to the all-solenoids-off mode tobe described below is thereby prohibited.

Specifically, when the spool 32 p of the second clutch apply relay valve32 is in the left half position, in the all-solenoids-off mode to bedescribed below, the forward range pressure P_(D), which is input to theinput port 32 e of the second clutch apply relay valve 32 as reverseinput pressure, is input to the discharge port SL1 d of the linearsolenoid valve SL1 from the output port 32 f as reverse input pressure,output from the output port SL1 b, supplied to the hydraulic servo 51,and thereby the first clutch C-1 is engaged. That is, due to the thirdforward speed being attained, in this state, when transitioning to theall-solenoids-off mode at a high speed equal to or greater than, forexample, the fifth forward speed, downshifting of two or more speedswill occur.

In the fifth forward speed, in addition to the linear solenoid valve SL1being turned on, the linear solenoid valve SL2 is turned on, the forwardrange pressure P_(D), which is input to the input port SL2 a via the B-2apply control valve 35, is regulated and output to the hydraulic servo52 as the engagement pressure P_(C2), and the second clutch C-2 isengaged. Thereby, coupled with the engagement of the first clutch C-1described above, the fifth forward speed is attained.

In the sixth forward speed, in addition to the linear solenoid valve SL2being turned on, the linear solenoid valve SL4 is turned on, the linepressure P_(L), which is input to the input port SL4 a via the secondclutch apply relay valve 32, is regulated and output to the hydraulicservo 54 as the engagement pressure P_(C4), and the fourth clutch C-4 isengaged. Thereby, coupled with the engagement of the second clutch C-2described above, the sixth forward speed is attained.

Note that at this time, similarly, when the sixth forward speed has notbeen attained, a state may have occurred in which the line pressureP_(L) is not input to the input port SL4 a because the second clutchapply relay valve 32 is stuck in the left half position, andtransitioning to the all-solenoids-off mode is prohibited.

Note that similarly while the spool 32 p of the second clutch applyrelay valve 32 is in the left half position, in the all-solenoids-offmode described below, the forward range pressure P_(D), which is inputto the input port 32 e of the second clutch apply relay valve 32 asreverse input pressure, is input to the discharge port SL 1 d of thelinear solenoid valve SL1 from the output port 32 f as reverse inputpressure, is then output by the output port SL1 b, supplied to thehydraulic servo 51, and the first clutch C-1 is thereby engaged. Thatis, due to the third forward speed being attained, in this state, whentransitioning to the all-solenoids-off mode at a high speed equal to orgreater than, for example, the fifth forward speed, downshifting of twoor more speeds will occur.

In the seventh forward speed, in addition to the linear solenoid valveSL2 being turned on, the linear solenoid valve SL3 is turned on, theforward range pressure P_(D), which is input to the input port SL3 a, isregulated and output to the hydraulic servo 53 as the engagementpressure P_(C3), and the clutch C-3 is engaged. Thereby, coupled withthe engagement of the second clutch C-2 described above, the seventhforward speed is attained.

In the eighth forward speed, in addition to the linear solenoid valveSL2 being turned on, the linear solenoid valve SL5 is turned on, theline pressure P_(L), which is input to the input port SL5 a, isregulated and output to the hydraulic servo 61 as the engagementpressure P_(B1), and the first brake B-1 is engaged. Thereby, coupledwith the engagement of the second clutch C-2 described above, the eighthforward speed is attained.

Note that, in the worst case, when the fifth forward speed through theeighth forward speed are not attained, a state may have occurred inwhich the forward range pressure P_(D) is not input to the input portSL2 a because the B-2 apply control valve 35 is stuck at the right halfposition, and thus, the second clutch C-2 is not engaged. When such astate has been identified, a fail-safe operation will be carried out.

Configuration of the Simultaneous Engagement Prevention MechanismPortion in the Hydraulic Control Apparatus

Next, the functional portion in the hydraulic control apparatus 20 thatmainly carries out the simultaneous engagement prevention will beexplained with reference to FIG. 6. A first clutch apply control valve41 is interposed between the output port SL1 b of the linear solenoidvalve SL1 and the hydraulic servo 51 as described above. The output portSL3 b of the linear solenoid valve SL3 is directly connected to thehydraulic servo 53. A second clutch apply control valve 43 is interposedbetween the output port SL4 b of the linear solenoid valve SL4 and thehydraulic servo 54 as described above. The B-1 apply control valve 44 isinterposed between the output port SL5 b of the linear solenoid valveSL5 and the hydraulic servo 61 as described above.

In addition, as described above, the B-2 apply control valve 35 and thelinear solenoid valve SL3 are interposed between the manual shift valve23 (refer to FIG. 4 and FIG. 5) and the hydraulic servo 52, and at thesame time, the B-2 apply control valve 35, the B-2 control valve 36, andthe B-2 check valve 37 are interposed between the manual shift valve 23and the hydraulic servo 62.

The first clutch apply control valve 41 includes a spool 41 p whose landportion is formed such that the diameter thereof gradually becomeslarger from the top to the bottom of the figure, a spring 41 sa thaturges the spool 41 p upwards in the figure, a plunger 41 r that can abutthe spool 41 p, and a spring 41 sb that is disposed in a compressedstate between the spool 41 p and the plunger 41 r. In addition, insequence from the above the spool 41 p in the figure, the first clutchapply control valve 41 includes an oil chamber 41 a, an oil chamber 41b, an oil chamber 41 c, an input port 41 d, an output port 41 e, and anoil chamber 41 f.

The engagement pressure P_(C2) that is supplied to the hydraulic servo52 is input to the oil chamber 41 a, and the largest engagement pressureamong the P_(C3), P_(C4), and P_(B1) engagement pressures that issupplied to the hydraulic servos 53, 54, and 61 is input to the oilchamber 41 b by the signal check valve 42, and furthermore, theengagement pressure P_(C1) to be supplied to the hydraulic servo 51 isinput to the oil chamber 41 c. In contrast, the line pressure P_(L) isinput to the oil chamber 41 f, and coupled with the urging force of thespring 41 sa, the spool 41 p is urged upward (to the left halfposition).

Thereby, for example, when the engagement pressure P_(C1) that is inputto the oil chamber 41 c, the engagement pressure P_(C2) that is inputinto the oil chamber 41, or any of the engagement pressures P_(C1),P_(C3), and P_(B1) that are input to the oil chamber 41 f aresimultaneously input, the input port 41 d is interrupted due to the linepressure P_(L) of the oil chamber 41 f and the urging force of thespring 41 sa being overcome, and the supply of the engagement pressureP_(C1) to the hydraulic servo 51 is stopped. Thus, the simultaneousengagement between the first clutch C-1, the second clutch C-2, and thethird clutch C-3, the simultaneous engagement between the first clutchC-1, the second clutch C-2, and the fourth clutch C-4, and thesimultaneous engagement between the first clutch C-1, the second clutchC-2, and the first brake B-1 are prevented, and the engagement betweenthe second clutch C-2 and the third clutch C-3, the second clutch C-2and the fourth clutch C-4, and the second clutch C-2 and the first brakeB-1 are permitted.

Note that when no oil pressure is generated because the engine isstopped, because the spring 41 sb locks only the plunger 41 r in theright half position, during normal operation, the plunger 41 r of thefirst clutch apply control valve 41 being supported in the left halfposition is prevented, and in cases other than failure, when no oilpressure is generated because the engine has stopped, while operatingduring a failure, the prevention of an actual hindrance when actuallymoving to the right half position can be implemented by moving only theplunger 41 r to the right half position.

The second clutch apply control valve 43 includes a spool 43 p whoseland portion is formed such that the diameter thereof gradually becomeslarger from the top to the bottom of the figure, a spring 43 sa thaturges the spool 43 p upwards in the figure, a plunger 43 r that can abutthe spool 43 p, and a spring 43 sb that is disposed in a compressedstate between the spool 43 p and the plunger 43 r. In addition, insequence from the above the spool 43 p in the figure, the second clutchapply control valve 43 includes an oil chamber 43 a, an oil chamber 43b, an input port 43 c, an output port 43 d, and an oil chamber 43 e.

The engagement pressure P_(C3) that is supplied to the hydraulic servo53 is input to the oil chamber 43 a, and the engagement pressure P_(C4)that is supplied to the hydraulic servo 54 is input to the oil chamber43 b. In contrast, the line pressure P_(L) is input to the oil chamber43 e, and coupled with the urging force of the spring 43 sa, the spool43 p is pressed upward (to the left half position).

Thereby, when, for example, the engagement pressure P_(C4) is input tothe oil chamber 43 b and the engagement pressure P_(C3) is input to theoil chamber 41 a simultaneously, the input port 43 c is interruptedbecause the line pressure P_(L) of the oil chamber 41 e and the urgingforce of the spring 43 sa are overcome, the supply of the engagementpressure P_(C4) to the hydraulic servo 54 is stopped, and thesimultaneous engagement between the third clutch C-3 and the fourthclutch C-4 is thereby prevented, and the engagement of the third clutchC-3 is thereby permitted.

Note that when no oil pressure is generated because the engine isstopped, the spring 43 sb locks only the plunger 43 r in the right halfposition, and thus during normal operation, the plunger 43 r of thesecond clutch apply control valve 43 being maintained continuously inthe left half position is prevented. In cases other than failure, whenno oil pressure is generated because the engine has stopped, only theplunger 43 r is operated in the right half position, and thus whileoperating during a failure, the prevention of an actual hindrance whenactually moving to the right half position can be implemented by movingonly the plunger 43 r to the right half position.

The B-1 apply control valve 44 includes a spool 44 p whose land portionis formed such that the diameter thereof gradually becomes larger fromthe top to the bottom of the figure, a spring 44 sa that urges the spool44 p upward in the figure, a plunger 44 r that can abut the spool 44 p,and a spring 44 sb that is disposed in a compressed state between thespool 44 p and the plunger 44 r. In addition, in sequence from the abovethe spool 44 p in the figure, the B-1 apply control valve 44 includes anoil chamber 44 a, an oil chamber 44 b, an oil chamber 44 c, an inputport 44 d, an output port 44 e, and an oil chamber 44 f.

The engagement pressure P_(C4) that is supplied to the hydraulic servo54 is input to the oil chamber 44 a, the engagement pressure P_(C3) thatis supplied to the hydraulic servo 53 is input to the oil chamber 44 b,and the engagement pressure P_(B1) that is supplied to the oil chamber61 is input to the oil chamber 43 c. In contrast, the line pressureP_(L) is input to the oil chamber 44 f, and coupled with the urgingforce of the spring 44 sa, the spool 44 p is pressed upward (to the lefthalf position).

In the B-1 apply control valve 44, while the engagement pressure P_(C1),which is supplied to the hydraulic servo 61 of the first brake B-1, isinput to the oil chamber 44 c, the spool 44 p and the plunger 44 r arein the right half position when one of the engagement pressure P_(C3) ofthe third clutch C-3 and the engagement pressure P_(C4) of the fourthclutch C-4, which are not simultaneously engaged by the second clutchapply control valve 43, is input to the oil chamber 44 a or the oilchamber 44 b.

Thereby, when, for example, the engagement pressure P_(B1) is input tothe oil chamber 44 c, the engagement pressure P_(C4) is input to the oilchamber 44 a, or the engagement pressure P_(C3) is input to the oilchamber 44 b simultaneously, the input port 44 d is interrupted becausethe line pressure P_(L) of the oil chamber 44 f and the urging force ofthe spring 44 sa are overcome, and the supply of the engagement pressureP_(B1) to the hydraulic servo 61 is stopped. Thus, the simultaneousengagement of the first brake B-1, the third clutch C-3, and the fourthclutch C-4 is prevented, and the engagement of the third clutch C-3 andthe fourth clutch C-4 is permitted.

Note that when no oil pressure is generated because the engine isstopped, the spring 44 sb locks only the plunger 44 r in the right halfposition, and thus during normal operation, the plunger 44 r of the B-1apply control valve 44 being held continuously in the left half positionis prevented. In cases other than failure, when no oil pressure isgenerated because the engine has stopped, by moving only the plunger 44r to the right half position, the prevention of an actual hindrance whenactually moving to the right half position can be implemented whileoperating during a failure.

The B-2 apply control valve 35 is locked in the left half position whenany of the engagement pressures P_(C3), P_(C4), or P_(B1) is input tothe oil chamber 35 f as described above, irrespective of the input ofthe signal pressure P_(SR). In addition, when none of the engagementpressure P_(C3), P_(C4), or P_(B1) is input to the oil chamber 35 f andthe signal pressure P_(SR) of the solenoid valve SR is input, the B-2apply control valve 35 is set to the right half position because theurging force of the spring 35 s is overcome.

Thereby, when any of the engagement pressures P_(C3), P_(C4), or P_(B1)are input to the oil chamber 35 f, the forward range pressure P_(D) issupplied only to the linear solenoid valve SL2, and thus, because theforward range pressure P_(D) is not supplied to the hydraulic servo 62,the simultaneous engagement of any of the third clutch C-3, the fourthclutch C-4, and the first brake B-1 with the second brake B-2 isprevented. In addition, when the input port 35 d and the output port 35e to SL2 are communicating, because the communication between the inputport 35 d and the output port 35 c to the B-2 control valve 36 isinterrupted, the simultaneous engagement between the second clutch C-2and the second brake B-2 is prevented.

As has been described above, the simultaneous engagement of two amongthe third clutch C-3, the fourth clutch C-4, and the first brake B-1 canbe prevented by the second clutch apply control valve 43 and the B-1apply control valve 44. In addition, the simultaneous engagement of anyof the third clutch C-3, the fourth clutch C-4, and the first brake B-1with the second brake B-2 can be prevented, and the simultaneousengagement between the second clutch C-2 and the second brake B-2 can beprevented by the B-2 apply control valve 35. Furthermore, thesimultaneous engagement of any among the third clutch C-3, the fourthclutch C-4, and the first brake B-1 with the second clutch C-2 and thefirst clutch C-1 is prevented by the first clutch apply control valve41. Thereby, in the forward range, necessarily only the first clutch C-1can engage simultaneously with the second brake B-2, while thesimultaneous engagement of three friction engagement elements (clutchesand brakes) can be reliably prevented.

Operation During All-Solenoids-Off Fail

Next, the all-solenoids-off fail state will be explained with referenceto FIG. 5. In the hydraulic control apparatus 20 according to anexemplary embodiment of the present invention for an automatictransmission, excluding the case in which, for example, the sticking ofthe linear solenoid valve SL4 described above has been detected, when afailure of the other solenoid valves, any of the switching valves, anyof the control valves or the like, has been detected, all of thesolenoid valves transit to the all-solenoids-off fail mode. Note that,for example, even in the case in which a severed wire or short hasoccurred, similarly all of the solenoids are set to off, and thus in thepresent specification, these states are also included in theall-solenoids-off fail mode.

First, during normal operation, even if the engine starts up and theline pressure P_(L) is generated from the primary regulator valve 25 byactuating the oil pump 21 because the ignition and the solenoid valve SRhave been turned on, the signal pressure P_(SR) is not output. Thus, inthe second clutch apply relay valve 32, the urging force of the spool 32s and, via the spool 33 p, the urging force of the spring 33 s, actupward in FIG. 5 on the spool 32 p, and the spool 32 p is thereby set inthe right half position.

At the right half position of this spool 32 p, the line pressure P_(L)input to the input port 32 b is output as a lock pressure from theoutput port 32 c to the input port SL4 a of the linear solenoid valveSL4, the oil chamber 33 a of the lock pressure delay valve 33, and theinput port 33 b. Thus, the spool 33 p of the lock pressure delay valve33 is pressed downward in FIG. 5 to the left half position, the inputport 33 b and the oil chamber 32 g are communicated, the line pressureP_(L) is input to the oil chamber 32 g as lock pressure, and the spool32 p is locked in the upper position. In this locked state, the engineis stopped, the oil pump 21 is stopped, and the locked state ismaintained until the line pressure P_(L) is no longer generated.

Here, for example, when the all-solenoids-off fail mode occurs due tosome cause while a vehicle is traveling in the forward range, in thesecond clutch apply relay valve 32, all of the solenoid valves areturned off (a failure has occurred) when the spool 32 p is locked by thelock pressure based on the line pressure P_(L). At this time, becauseall of the solenoid valves are turned off, only the solenoid valve SR,which is a normally open valve, outputs the signal pressure P_(SR), andbecause the other solenoid valves have stopped the output of the signalpressures and the engagement pressures, in particular, in the linearsolenoid valves SL1, SL2, and SL3, the output ports SL1 b, SL2 b, andSL3 b, and the discharge ports SL1 d, SL2 d, and SL3 d are communicated.

In contrast, in the second clutch apply relay valve 32, the signalpressure P_(SR) is input to the oil chamber 32 a, but because the linepressure P_(L) is input to the oil chamber 32 g as lock pressure, thespool 32 p is maintained locked in the upper position.

Note that in the worst case, even if the lock pressure delay valve 33 isstuck in the left half position in the upper portion of the figure andthe line pressure P_(L) is not input as lock pressure to the oil chamber32 g of the second clutch apply relay valve 32, the spool 33 p of thelock pressure delay valve 33 is structured so as to abut the spool 32 pof the second clutch apply relay valve 32, and the state in which thespool 32 p is similarly thereby locked in the upper position ismaintained.

In addition, in the first clutch apply relay valve 34, the signalpressure P_(SR) of the solenoid valve SR is input to the oil chamber 34a, and the spool 34 p is set in the left half position because theurging force of the spring 34 s is overcome. Thereby, the forward rangepressure P_(D) that is input to the input port 34 k is output from theoutput ports 34 d and 34 e as a fail engagement pressure, and then isinput to the discharge port SL3 d of the linear solenoid valve SL3 andthe input port 32 e of the second clutch apply relay valve 32.

The forward range pressure P_(D) that has been input to the dischargeport SL3 d of the linear solenoid valve SL3 as fail engagement pressureis output from the output port SL3 b of the linear solenoid valve SL3,is supplied to the hydraulic servo 53, and the third clutch C-3 isthereby engaged. In addition, because the spool 32 p is locked in theright half position, the forward range pressure P_(D), which is input asreverse input pressure to the input port 32 e of the second clutch applyrelay valve 32, is input to the discharge port SL2 d of the linearsolenoid valve SL2 from the output port 32 d as the reverse inputpressure, is then output from the output port SL2 b, is supplied to thehydraulic servo 52, and the second clutch C-2 is thereby engaged.

As shown above, in the all-solenoids-off fail mode while the vehicle istraveling in the forward range, the seventh forward speed, in which thesecond clutch C-2 and the third clutch C-3 have been engaged, is set.

In contrast, subsequently, for example, when the vehicle is temporarilystopped and the engine is stopped, the line pressure P_(L) is no longergenerated, and in the second clutch apply relay valve 32 and the lockpressure delay valve 33, both the spool 32 p and the spool 33 p are setin the right half position due to the urging pressure of the spring 32 sand the spring 33 s. In addition, subsequent to this, when the engine isrestarted, the oil pump 21 is actuated and line pressure P_(L) isthereby generated, but because the solenoid valve SR is turned off andthe signal pressure P_(SR) is input to the oil chamber 32 a, the signalpressure P_(SR) acts downward in the figure against the urging force ofthe spring 32 s and the urging force of the spring 33 s, and the spool32 p is switched to the left half position. Thereby, the line pressureP_(L) is not output from the output port 32 c because the input port 32b is interrupted, and the line pressure P_(L) is not input to the oilchamber 32 g as lock pressure.

In addition, in this case, even if, for example, the line pressure P_(L)flows from the input port 32 b and a small amount of the lock pressureis output from the output port 33 c before the spool 32 p is switched tothe left half position, because the inflow of lock pressure from theorifices 71 and 72 is dampened and time is required for the spool 33 pof the lock pressure delay valve 33 to be switched to the left halfposition, and the input of the lock pressure to the oil chamber 32 g isdelayed, the signal pressure P_(SR) is input to the oil chamber 32 abefore the spool 32 p is locked in the upper position, and the spool 32p is reliably switched thereby to the lower position.

Note that in the present exemplary embodiment, the case was explained inwhich the line pressure P_(L) acted as a lock force on the oil chamber33 a of the lock pressure delay valve 33, but this may be modified suchthat the forward range pressure P_(D) will act instead of the lockpressure (i.e. the line pressure P_(L)). In this case, because theengine is restarted and the oil pressure does not act on the oil chamber33 a until the shift position is set in the forward range, inputting thelock pressure to the oil chamber 32 g can be delayed more reliably.

In addition, in the second clutch apply relay valve 32, when the spool32 p is switched to the left half position, the forward range pressureP_(D), which has been output from the output ports 34 d and 34 e of thefirst clutch apply relay valve 34 described above and input to the inputport 32 e, is input as fail engagement pressure to the discharge portSL1 d of the linear solenoid valve SL1 from the output port 32 f, isoutput from the output port SL1 b, is supplied to the hydraulic servo51, and the first clutch C-1 is thereby engaged.

As explained above, after the engine has restarted in theall-solenoids-off fail mode, the third forward speed, in which the firstclutch C-1 and the third clutch C-3 have been engaged, is set.

Configuration of the Reverse Shifting Function and the Lock-up FunctionPortions in the Hydraulic Control Apparatus

Next, the functional portions that mainly carry out the reverse shiftingcontrol and the lock-up control in the present hydraulic controlapparatus 20, which are the essential components of an exemplaryembodiment of the present invention, will be explained with reference toFIG. 7. Note that the manual shift valve 23, the linear solenoid valveSL4, the B-2 control valve 36, the B-2 check valve 37 and the like havebeen explained in relation to the forward shift control described above,and thus the explanation thereof has been omitted.

The solenoid valve SL is a normally closed valve, and inputs a modulatorpressure P_(MOD) to the input port Sa (also used by the solenoid valveSR described above). The solenoid valve SL is turned on while thevehicle is traveling in reverse and while the lock-up clutch 10 isactuated, and outputs the signal pressure P_(SL) from the output portSLb. The output port SLb is connected to the oil chamber 31 a of thelock-up relay valve 31 described below and the oil chamber 45 a of theC-4 relay valve 45, and while turned on, outputs the signal pressureP_(SL) to the oil chambers 31 a and 45 a.

The lock-up relay valve 31 includes a spool 31 p and a spring 31 s thaturges the spool 31 p upward in the figure, and above the spool 31 p inthe figure, includes an oil chamber 31 a, an input/output port 31 b, anoutput port 31 c, an input port 31 d, an input port 31 e, an input port31 f, and an oil chamber 31 g.

During the disengagement of the lock-up clutch 10 while the vehicle istraveling forward, the signal pressure P_(SL) is not input to the oilchamber 31 a because the solenoid valve SL is turned off, and due to theurging force of the spring 31 s, the spool 31 p is set in the right halfposition (first position). In addition, when the spool 31 p is in theright half position, the signal pressure P_(SLU) is input to the inputport 31 b from the linear solenoid valve SLU, and the signal pressureP_(SLU) is output to the oil chamber 36 a of the B-2 control valve 36from the output port 31 c.

In addition, a secondary pressure P_(SEC), which is regulated by thesecondary regulator valve 26 described above, is input to the input port31 e, and when the spool 31 p is set in the right half position, thesecondary pressure P_(SEC) is output to the lock-up-off port 10 a of thetorque converter 7 from the input/output port 31 d. The secondarypressure P_(SEC) that is input into the torque converter 7 from the port10 a is circulated and discharged from the port 10 a, which is also usedfor lock-up-on, and drained by the drain port (not illustrated) via theinput/output port 31 f (or supplied to a lubricating fluid path or thelike (not illustrated)).

During the engagement of the lock-up clutch 10 while traveling forward,when the solenoid valve SL is tuned on, the signal pressure P_(SL) isinput to the oil chamber 31 a, and the spool 31 p is set in the lefthalf position (second position) because the urging force of the spring31 s is overcome. Thus, the signal pressure P_(SLU) that is input to theinput port 31 b is interrupted, and at the same time, the secondarypressure P_(SEC) that is input to the input port 31 e is output to thelock-up-on port 10 b from the input/output port 31 f, and the lock-upclutch 10 is engaged by being pressed.

When the vehicle is traveling in reverse, the reverse range pressureP_(R) is input to the oil chamber 31 g from the manual shift valve 23,and the spool 31 p of the lock-up relay valve 31 is locked in the righthalf position. Thereby, even if the signal pressure P_(SL) is input tothe oil chamber 31 a, the urging force of the spring 31 s and thereverse range pressure P_(R) of the oil chamber 31 g are coupled, andthe spool 31 p is maintained in the right half position.

The C-4 relay valve 45 includes a spool 45 p and a spring (urgingdevice) 45 s that urges the spool 45 p downward in FIG. 7, and above thespool 45 p, the C-4 relay valve 45 further includes an oil chamber 45 a,an input port 45 b, an output port 45 c, an input port 45 d, and an oilchamber 45 e.

When the vehicle is traveling in the forward range (that is, when thereverse range pressure P_(R) is not output) and the solenoid valve SL isturned off (that is, while the lock-up clutch 10 is disengaged), thesignal pressure P_(SL) is not output to the oil chamber 45 a, but thespool 45 p is set in the left half position (normal position) because ofthe urging force of the spring 45 s. In addition, when the vehicle istraveling in the forward range, even if the solenoid valve SL is turnedon (that is, while the lock-up clutch 10 is engaged) and the signalpressure P_(SL) is input to the oil chamber 45 a, coupled with theurging force of the spring 45 s, the spool 45 p is set in the left halfposition.

When the spool 45 p is in the left half position, the engagementpressure P_(C4) from the linear solenoid valve SL4 is input to the inputport 45 d and is output to the hydraulic servo 54 from the output port45 c, and thus, in the fourth forward speed and the sixth forward speed,the hydraulic servo 54 is regulated and controlled linearly by thelinear solenoid valve SL4.

Next, the control during reverse travel will be explained. In thereverse range during normal operation, the reverse range pressure P_(R)is output from the output port 23 d of the manual shift valve 23. Thus,in the C-4 relay valve 45, the reverse range pressure P_(R) is input tothe oil chamber 45 e, but the solenoid valve SL is turned on, the signalpressure P_(SL) is input to the oil chamber 45 a, and coupled with theurging force of the spring 45 s, the spool 45 p is set in the left halfposition. Thereby, even during reverse travel, the engagement pressureP_(C4) from the linear solenoid valve SL4 is output to the hydraulicservo 54.

In addition, in the B-2 control valve 36, because the signal pressureP_(SLU) of the linear solenoid valve SLU is not output, the B-2 controlvalve 36 is locked in the right half position, and the reverse rangepressure P_(R) that is input to the input port 36 d is output as theengagement pressure P_(B2) from the output port 36 e. The engagementpressure P_(B2) that is output from the output port 36 e is input to theinput port 37 b of the B-2 check valve 37, and is output by the outputport 37 c to supply the hydraulic servo 62. Thereby, the fourth clutchC-4 and the second brake B-2 are engaged, and the second reverse speedis attained.

Note that in the reverse range, there are cases where the engagementpressure P_(B2) from the output port 36 e is not output due to the B-2control valve 36 becoming stuck in the left half position. Thus, whenthe sticking of the B-2 control valve 36 is detected by, for example,the reverse speed not being established, the B-2 control valve 36 isswitched to the left half position by turning the solenoid valve SR offand by applying the signal pressure P_(SR) to the first clutch applyrelay valve 34, and thereby the reverse range pressure P_(R) is input tothe input port 35 b via the port 34 i and the port 34 h, and the reverserange pressure P_(R) is output to the B-2 control valve 36 from theoutput port 35 c.

However, the manual shift valve 23 is constructed so as to be connectedto a shift lever disposed at the driver's seat via a detent mechanismand a link mechanism (or a shift-by-wire apparatus) that are notillustrated, and the spool 23 p is driven in the spool movementdirection (linear movement direction) by a linkage to a fan-shapeddetent plate, which is rotated by the operation of the shift lever. Atthe same time, due to the detent lever that urges the detent plate ineach shift range position, the manual shift valve 23 does not stop at anintermediate position within these range positions. This detent platethat is rotated has a support axle that is integrally attached at thecenter of rotation, and an angle sensor that detects the angle ofrotation of the support axle is provided on the end of this supportaxle. Specifically, this angle sensor detects the angle of the detentplate, that is, it can detect the spool position of the manual shiftvalve 23 that is driven by the linkage to the detent plate.

Based on the detection of this angle sensor (below, referred to simplyas a “spool position sensor” to facilitate understanding), whendetecting that the vehicle has switched from the non-travel range(specifically, the parking range and the neutral range) to the forwardrange, forward start control is carried out in which, for example, thelinear solenoid valve SL1 is turned on by the electronic control unit(for example, an ECU) and the first forward speed described above isattained (the second forward speed or the third forward speed may beestablished). In addition, when a switch from the non-travel range tothe reverse range has been detected, reverse start control is carriedout in which the solenoid valve SL and the linear solenoid valve SL4 areturned on, and the second forward speed described above is established.

However, as described above, for example, in the case in which the spoolposition sensor has failed, the shift position (shift range position)cannot be detected, and there is a concern that whether one of thesolenoid valves should be turned on cannot be determined. In addition,in the case in which, for example, the shift position cannot bedetected, none of the solenoid valves are turned on, which means thatengagement pressure is not supplied to any of the hydraulic servos, andthus, the vehicle is in a neutral state in which the drive power fromthe engine is not transferred to the vehicle wheels via the shift changemechanism 2.

Thus, in the present hydraulic control apparatus according to anexemplary embodiment of the present invention for an automatictransmission, in the case in which the shift position cannot be notdetected, forward start control is carried out in which, similar to thefirst forward speed, the solenoid valve is turned on, that is, only thelinear solenoid valve SL1 is turned on. At this time, if the actualshift position is in the forward range, the first forward speeddescribed above is established as explained above, and thus theexplanation of the first forward speed is omitted.

In the case in which the shift position cannot be detected and theactual shift position is in the reverse range, because first the linearsolenoid valve SL1 is turned on and the forward range pressure P_(D) issupplied to the input port SL1 a of the linear solenoid valve SL1 (referto FIG. 4 and FIG. 5), the engagement pressure P_(C1) is not supplied tothe hydraulic servo 51, and thus, the first clutch C-1 is not engaged.

In contrast, as shown in FIG. 7, in the case in which the solenoid valveSL and the linear solenoid valve SL4 are turned off, after the reverserange pressure P_(R) has been output from the output port 23 b of themanual shift valve 23, it is input to the oil chamber 45 e of the C-4relay valve 45, and because the urging force of the spring 45 s isovercome, the spool 45 p is set in the right half position (failposition). Thereby, the reverse range pressure P_(R) that is input tothe input port 45 b is output from the output port 45 c, is supplied tothe hydraulic servo 54, and the fourth clutch C-4 is thereby engaged.

In addition, in the B-2 control valve 36, the spool 36 b is set in theright half position due to the urging force of the spring 36 s, thereverse range pressure P_(R) that is input to the input port 36 d isoutput from the output port 36 e and supplied to the hydraulic servo 62via the B-2 check valve 37, and the second brake B-2 is thereby engaged.Thus, the fourth clutch C-4 and the second brake B-2 are engaged, andthe second reverse speed is attained.

In this manner, even in the case in which, for example, the shiftposition cannot be detected, in an exemplary embodiment of the presentinvention, the hydraulic control apparatus 20 for an automatictransmission, due to the actual spool position in the manual shift valve23, the first reverse speed and the second reverse speed can beestablished.

Note that in the present exemplary embodiment, the case was explained inwhich the spool position sensor fails and the linear solenoid valve SL4and the solenoid valve SL are turned off (de-energized) due to carryingout forward start control irrespective of the shift position. However,during the all-solenoids-off fail mode described above, the case is thesame, that is, even when the linear solenoid valve SL4 and the solenoidvalve SL are turned off due to the all-solenoids-off condition, theengagement of the fourth clutch C-4 is enabled due to the reverse rangepressure P_(R).

Outline of the Invention

According to an exemplary embodiment of the present invention asexplained above, in the case in which, for example, the C-4 relay valve45 communicates the engagement pressure P_(C4) from the linear solenoidvalve SL4 to the hydraulic servo 54 by being locked in the left halfposition, which is the normal position, when the signal pressure P_(SL)of the solenoid valve SL is input and the all-solenoids-off fail mode orthe shift range position cannot be detected, even in a failure in whichthe linear solenoid valve SL4 and the solenoid valve SL arede-energized, the reverse range pressure P_(R) is communicated to thehydraulic servo 54 by being switched to the right half position, whichis the fail position, because the reverse range pressure P_(R) when themanual shift valve 23 is switched to the reverse range position. Thus,during normal operation, by supplying the engagement pressure P_(C4)that is output from the linear solenoid valve SL4 to the hydraulic servo54, it is possible to regulate the engagement pressure P_(C4) in alinear manner so as not to cause, for example, shift shock, it ispossible to smoothly establish the reverse speed, it is possible toestablish the reverse speed by supplying the reverse range pressureP_(R) to the hydraulic servo 54 even during a failure, and it ispossible for the vehicle to travel in reverse even during a failure.

In addition, the C-4 relay valve 45 includes a spool 45 p that switchesto the left half position, which is the normal position, or the righthalf position, which is the fail position, a spring 45 s that urges thespool 45 p toward the left half position, which is the normal position,an oil chamber 45 a in which the signal pressure P_(SL) of the solenoidvalve SL acts on the spool 45 p in the direction of the left halfposition, which is the normal position, and an oil chamber 45 e in whichthe reverse range pressure P_(R) acts on the spool 45 p in the directionof the right half position, which is the fail position. Thus, the C-4relay valve 45 is locked in the normal position when the signal pressureP_(SL) of the solenoid valve SL is input, and can be switched to theright half position, which is the fail position, by the reverse rangepressure P_(R) during a failure.

Furthermore, the lock-up relay valve 31 is provided that is switchedfrom the right half position to the left half position when the signalpressure P_(SL) of the solenoid valve SL is input and locks in the righthalf position when the reverse range pressure P_(R) is input. Thus,while hydraulic control of the lock-up clutch using the solenoid valveSL in the forward range is possible, in the reverse range P_(R), it ispossible to output the signal pressure P_(SL) of the solenoid valve SLin order to establish the reverse speed.

In addition, during a failure in which the range position of the manualshift lever 23 is not detected by the spool position sensor, becauseforward startup control is carried out, in which the solenoid valve SL1is energized, when the manual shift valve 23 is in the forward rangeposition, the forward speed is attained and the vehicle can travelforward. In addition, while it is possible that the engagement pressureP_(C1) will not be output from the linear solenoid valve SL1 when theforward range pressure P_(D) is not output and that this could obstructattaining the first forward speed, the C-4 relay valve 45 is switched tothe right half position, which is the fail position, due to the reverserange pressure P_(R), it is possible to establish thereby the reversespeed by supplying the reverse range pressure P_(R) to the hydraulicservo 54, and reverse travel of the vehicle is thereby possible.

Note that in the exemplary embodiment of the present invention explainedabove, an example was explained in which the hydraulic control apparatus20 is used in an automatic transmission capable of eight forward speedsand one reverse speed, but of course, this is not limiting, and thepresent invention can be used in any staged automatic transmission.

In addition, in the present exemplary embodiment, an example wasexplained in which a lock-up relay valve 31 is used as the secondswitching valve and the engagement control of the lock-up clutch duringforward travel is carried out by the solenoid valve SL, but this is notlimiting. The present exemplary embodiment can be applied to any valvein which any type of hydraulic control is carried out by switching aport that inputs and outputs hydraulic pressure during forward travel.

1. A hydraulic control apparatus, for an automatic transmission, theautomatic transmission establishing a plurality of shift speedsaccording to an engagement state of a plurality of friction engagementelements that are engaged and disengaged by respective hydraulic servos,and the hydraulic control apparatus, for the automatic transmission,comprises: a range switching valve that switches between any of aforward range position, a reverse range position, and non-travelpositions, outputs a forward range pressure when set to the forwardrange position, and outputs a reverse range pressure when set to thereverse range position; a first engagement pressure control solenoidvalve that outputs a first engagement pressure to a first hydraulicservo among the respective hydraulic servos of a first frictionengagement element among the plurality of friction engagement elements,that engages at least during reverse travel when energized, whereinreverse shift speed is established by energizing the first engagementpressure control solenoid valve when the range switching valve isswitched to the reverse range position during normal operation; a signalpressure output solenoid valve that is energized to output a signalpressure when the range switching valve is switched to the reverse rangeposition during normal operation; and a first switching valve that isinterposed between the first engagement pressure control solenoid valveand the first hydraulic servo, and is switched between a normal positionthat communicates the first engagement pressure to the first hydraulicservo and a fail position that communicates the reverse range pressureto the first hydraulic servo, wherein the first switching valve islocked in the normal position when the signal pressure of the signalpressure output solenoid valve is input, and is switched to the failposition due to the reverse range pressure when the range switchingvalve switches to the reverse range position during a failure in whichthe first engagement pressure control solenoid valve and the signalpressure output solenoid valve are de-energized.
 2. The hydrauliccontrol apparatus, for the automatic transmission, according to claim 1,wherein the first switching valve comprises a spool that is switchedbetween the normal position and the fail position, an urging device thaturges the spool toward the normal position, a first oil chamber in whichthe signal pressure of the signal pressure output solenoid valve acts onthe spool in a direction of the normal position; and a second oilchamber in which the reverse range pressure acts on the spool in thedirection of the fail position.
 3. The hydraulic control apparatus, forthe automatic transmission, according to claim 2, further comprising asecond switching valve that is switched from a first position to asecond position when the signal pressure of the signal pressure outputsolenoid valve is input and is locked in the first position when thereverse range pressure is input.
 4. The hydraulic control apparatus, forthe automatic transmission, according to claim 3, wherein the automatictransmission comprises a torque converter that includes a lock-upclutch, and the second switching valve outputs a lock-up clutchengagement pressure in order to engage the lock-up clutch when in thesecond position.
 5. The hydraulic control apparatus, for the automatictransmission, according to claim 4, further comprising: a range positiondetecting device that detects a range position of the range switchingvalve; and a second engagement pressure control solenoid valve thatoutputs a second engagement pressure to a second hydraulic servo amongthe respective hydraulic servos of a second friction engagement elementamong the plurality of friction engagement elements, that engages atleast during a forward start when energized, wherein the secondengagement pressure control solenoid valve outputs the second engagementpressure based on the forward range pressure, and during normaloperation, carries out forward start control in which the secondengagement pressure control solenoid valve is energized when a switchfrom the non-travel range position to the forward range position hasbeen detected in the range switching valve by the range positiondetecting device, and carries out reverse start control in which thefirst engagement pressure control solenoid valve and the signal pressureoutput solenoid valve are energized when a switch from the non-travelrange position to the reverse range position has been detected in therange switching valve by the range position detecting device, andcarries out forward start control during a failure in which the rangeposition of the range switching valve has not been detected by the rangeposition detecting device.
 6. The hydraulic control apparatus, for theautomatic transmission, according to claim 3, further comprising: arange position detecting device that detects a range position of therange switching valve; and a second engagement pressure control solenoidvalve that outputs a second engagement pressure to a second hydraulicservo of a second friction engagement element among the plurality offriction engagement elements that, engages at least during a forwardstart when energized, wherein, the second engagement pressure controlsolenoid valve outputs the second engagement pressure based on theforward range pressure, and during normal operation, carries out forwardstart control in which the second engagement pressure control solenoidvalve is energized when a switch from the non-travel range position tothe forward range position has been detected in the range switchingvalve by the range position detecting device, and carries out reversestart control in which the first engagement pressure control solenoidvalve and the signal pressure output solenoid valve are energized when aswitch from the non-travel range position to the reverse range positionhas been detected in the range switching valve by the range positiondetecting device, and carries out forward start control during a failurein which the range position of the range switching valve has not beendetected by the range position detecting device.
 7. The hydrauliccontrol apparatus, for the automatic transmission, according to claim 2,further comprising: a range position detecting device that detects arange position of the range switching valve; and a second engagementpressure control solenoid valve that outputs a second engagementpressure to a second hydraulic servo of a second friction engagementelement among the plurality of friction engagement elements, thatengages at least during a forward start when energized, wherein thesecond engagement pressure control solenoid valve outputs the secondengagement pressure based on the forward range pressure; and duringnormal operation, carries out forward start control in which the secondengagement pressure control solenoid valve is energized when a switchfrom the non-travel range position to the forward range position hasbeen detected in the range switching valve by the range positiondetecting device, and carries out reverse start control in which thefirst engagement pressure control solenoid valve and the signal pressureoutput solenoid valve are energized when a switch from the non-travelrange position to the reverse range position has been detected in therange switching valve by the range position detecting device, andcarries out forward start control during a failure in which the rangeposition of the range switching valve has not been detected by the rangeposition detecting device.
 8. The hydraulic control apparatus, for theautomatic transmission, according to claim 1, further comprising: asecond switching valve that is switched from a first position to asecond position when the signal pressure of the signal pressure outputsolenoid valve is input and is locked in the first position when thereverse range pressure is input.
 9. The hydraulic control apparatus, forthe automatic transmission, according to claim 8, wherein the automatictransmission comprises a torque converter that includes a lock-upclutch, and the second switching valve outputs a lock-up clutchengagement pressure in order to engage the lock-up clutch when in thesecond position.
 10. The hydraulic control apparatus, for the automatictransmission, according to claim 9, further comprising: a range positiondetecting device that detects a range position of the range switchingvalve; and a second engagement pressure control solenoid valve thatoutputs a second engagement pressure to a second hydraulic servo of asecond friction engagement element among the plurality of frictionengagement elements, that engages at least during a forward start whenenergized, wherein the second engagement pressure control solenoid valveoutputs the second engagement pressure based on the forward rangepressure; and during normal operation, carries out forward start controlin which the second engagement pressure control solenoid valve isenergized when a switch from the non-travel range position to theforward range position has been detected in the range switching valve bythe range position detecting device, and carries out reverse startcontrol in which the first engagement pressure control solenoid valveand the signal pressure output solenoid valve are energized when aswitch from the non-travel range position to the reverse range positionhas been detected in the range switching valve by the range positiondetecting device, and carries out forward start control during a failurein which the range position of the range switching valve has not beendetected by the range position detecting device.
 11. The hydrauliccontrol apparatus, for the automatic transmission, according to claim 8,further comprising: a range position detecting device that detects arange position of the range switching valve; and a second engagementpressure control solenoid valve that outputs a second engagementpressure to a second hydraulic servo of a second friction engagementelement among the plurality of friction engagement elements, thatengages at least during a forward start when energized wherein thesecond engagement pressure control solenoid valve outputs the secondengagement pressure based on the forward range pressure; and duringnormal operation, carries out forward start control in which the secondengagement pressure control solenoid valve is energized when a switchfrom the non-travel range position to the forward range position hasbeen detected in the range switching valve by the range positiondetecting device, and carries out reverse start control in which thefirst engagement pressure control solenoid valve and the signal pressureoutput solenoid valve are energized when a switch from the non-travelrange position to the reverse range position has been detected in therange switching valve by the range position detecting device, andcarries out forward start control during a failure in which the rangeposition of the range switching valve has not been detected by the rangeposition detecting device.
 12. The hydraulic control apparatus, for anautomatic transmission, according to claim 1, further comprising: arange position detecting device that detects a range position of therange switching valve; and a second engagement pressure control solenoidvalve that outputs a second engagement pressure to a second hydraulicservo of a second friction engagement element among the plurality offriction engagement elements, that engages at least during a forwardstart when energized wherein the second engagement pressure controlsolenoid valve outputs the second engagement pressure based on theforward range pressure; and during normal operation, carries out forwardstart control in which the second engagement pressure control solenoidvalve is energized when a switch from the non-travel range position tothe forward range position has been detected in the range switchingvalve by the range position detecting device, and carries out reversestart control in which the first engagement pressure control solenoidvalve and the signal pressure output solenoid valve are energized when aswitch from the non-travel range position to the reverse range positionhas been detected in the range switching valve by the range positiondetecting device, and carries out forward start control during a failurein which the range position of the range switching valve has not beendetected by the range position detecting device.